Author of the invention while at occupational therapy has noticed that human fingers are the most efficient tools in performing massaging therapy on damaged tissues around the scars. Among many available massaging devices one with the humanlike fingers is missing. Work on the project produced massaging device prototype with two unbendable fingers. Their massaging action was not as good though as an action of the straight thumb and bendable index finger or middle finger. Successful design of bendable finger has revealed a great opportunity for using it in the future development of the prosthetic hands. Upon review of the previous US patents in the field of mechanical fingers, hands and grasping devices and comparing their fingers and palm designs to the one presented here it becomes apparent that presented here solutions can make a real progress in creating practical and affordable prosthetic hand. Most of the previous designs are complicated, expensive and they give very little if any consideration to the esthetic side of the prosthesis. Those designs are more suitable for the robotic rather than for the human applications with exception of the few argued below. U.S. Pat. No. 4,685,929 J. Monestier. This invention provides soft gripping hand with the fingers of attractive humanlike appearance. However a fingers comprising of such a high number of elements would be very difficult or impossible to manufacture in humanlike dimensions. The other disadvantage would be their high cost. Another U.S. Pat. No. 7,655,051, M. Stark provides prosthetic hand with fingers biased in a closed position by springs and digits are opened by a cord attached to the dorsal side of the top digit. In this design gripping force of digits depends on the strength of a springs and it is believed that fingers would lose their humanlike size with the larger springs guaranteed a decent grip. Also it is hard to predict which phalange will start moving first upon release of the cord what would cause grips to be rather uncontrollable. The most appealing solutions for making a simple and inexpensive prosthetic hand are those by Frank L. Dale, U.S. Pat. No. 2,457,305. Dale teaches that it is possible to create prosthetic finger using just one element as a driving rod to bend finger and as a spring to straighten a finger. In my invention finger bending and straightening motion needs four elements a driving rod two tendons and a spring and although Dale's design is more simple it carries some crucial limitations compare to the design presented here; a) a digits of Dale's fingers need more space in front to place there a channel for a rod/spring element and fingers humanlike appearance may be compromised b) finger's bending motion will always start from the top digit contrary to the human fingers where all three digits are moving at the same time and while making most common grasping motion the Dale's fingers will have a tendency to slide off an objects attempted to be grasped from the top c) not having any adjustable elements to the finger's digits is a greatest limitation to Dale's finger comparing to my design where the middle digit's motion is regulated by the length of a first tendon or by an adjustable rod what allows to create a variety of prosthetic hands with different grips complementing individual needs as well as allowing to use finger in other applications like that in presented here massaging device where Dale's fingers would work improperly by pinching top portion of the flesh with a top digits instead of engaging larger portion of a fingers with a wider and deeper portion of the human body. Prosthetic hand with presented here fingers will not only look like the real one but will be able to perform a few simple tasks in it basic form as well as multiple tasks in it most developed and computerized form.
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